# Water Pistols and Children!

A while ago, I posted about some interesting problems posed in the Technology Review magazine.

• Jerry Grossman has equipped $n$ children with loaded water pistols and has them standing in an open field with no three of them in a straight line, such that the distances between pairs of them are distinct. At a given signal, each child shoots the closest other child with water. Show that if $n$ is any even number, then it is possible (but not necessarily the case) that every child gets wet. Show that if $n$ is odd, then necessarily at least one child stays dry.
• Each of logicians A, B, and C wears a hat with a positive integer on it. The number on one hat is the sum of the numbers on the other two. The logicians take turns making statements, as follows:
A: “I don’t know my number.”
B: “My number is 15.”
What numbers are on the hats of A and C?

I submitted my solutions (click here to read my submitted solutions) and lo and behold, one of the solutions got published in the latest Technology Review (click here)!